SwiftUI – Not clear how to handle the alert with asynchronous methods - swift

Question

I have to present an Alert on a view if the user taps on it.
My alert depends on several situations:
Item is purchased. Show the item.
Item have not be purchased. Show an alert telling the user the item have to be purchased. This alert must show two buttons, OK to purchase, Cancel to dismiss.
User taps to purchase the item.
Purchase is successful, show the item.
Purchase fails, show error.
This is how I did it.
class AlertDialog {
enum SelectedType {
case none
case purchase
case mustBePurchased
case purchaseError
}
var selectedType:SelectedType = .none
}
struct FilteredListItem: View {
#State var showAlert: Bool = false
private var alertDialog:AlertDialog?
var body: some View {
Text(item.termLowerCase)
.font(fontItems)
.foregroundColor(.white)
.onTapGesture {
DispatchQueue.main.async {
appStoreWrapper.verifyPurchase(productID: item.package!)
{ // run if purchased
purchased = true
} runIfNotPurchased: {
purchased = false
alertDialog!.selectedType = .mustBePurchased
showAlert = true
}
}
}
.alert(isPresented: $showAlert) {
if alertDialog!.selectedType == .purchase {
appStoreWrapper.purchase(productID: item.package!) {
// run if purchased
purchased = true
} runIfPurchaseFailed: { (error) in
alertDialog!.selectedType = .purchaseError
appStoreWrapper.purchaseError = error
showAlert = true
}
} else if alertDialog!.selectedType == .purchaseError {
let primaryButton = Alert.Button.default(Text("OK")) {
showAlert = false
}
return Alert(title: Text(appStoreWrapper.makeString("ERROR")),
message: Text(appStoreWrapper.purchaseError),
dismissButton: primaryButton)
}
let dismissButton = Alert.Button.default(Text(appStoreWrapper.makeString("CANCEL"))) {
showAlert = false
}
let primaryButton = Alert.Button.default(Text("OK")) {
appStoreWrapper.purchase(productID: item.package!) {
// run if purchased
purchased = true
} runIfPurchaseFailed: { (error) in
appStoreWrapper.purchaseError = error
alertDialog!.selectedType = .purchaseError
showAlert = true
print(erro)
}
}
return Alert(title: Text(appStoreWrapper.makeString("ERROR")),
message: Text(appStoreWrapper.purchaseError),
primaryButton: primaryButton,
secondaryButton: dismissButton)
}
This is my problem: the modifier .alert(isPresented: $showAlert) expects an Alert() to be returned, right? But I have these asynchronous methods
appStoreWrapper.verifyPurchase(productID: item.package!)
{ // run if purchased },
runIfNotPurchased: { }
that cannot return anything to the alert modifier. How do I do that? Is what I am doing right?

Answer 1

There's a lot going on in your code and you didn't post the code for appStoreWrapper, but here's some code that should be able to point you in the right direction.
FYI:
You can use a Button with an Action instead of using Text with .onTapGesture
The code within .Alert should only function to get an Alert. You shouldn't be doing other actions within the .Alert closure.
struct FilteredListItem: View {
#State var showAlert: Bool = false
private var alertDialog: AlertDialog?
var body: some View {
Button(action: {
verifyItem()
}, label: {
Text("ITEM NAME")
.foregroundColor(.white)
})
.accentColor(.primary)
.alert(isPresented: $showAlert, content: {
getAlert()
})
}
func verifyItem() {
// FUNCTION TO VERIFY ITEM HERE
var success = true //appStoreWrapper.verifyPurchase...
if success {
// Handle success
} else {
alertDialog?.selectedType = .mustBePurchased
showAlert.toggle()
}
}
func purchaseItem() {
// FUNCTION TO PURCHASE ITEM HERE
var success = true //appStoreWrapper.purchase...
if success {
// Handle success
} else {
alertDialog?.selectedType = .purchaseError
showAlert.toggle()
}
}
func getAlert() -> Alert {
guard let dialog = alertDialog else {
return Alert(title: Text("Error getting alert dialog."))
}
switch dialog.selectedType {
case .purchaseError:
return Alert(
title: Text("Error purchasing item."),
message: nil,
dismissButton: .default(Text("OK")))
case .mustBePurchased:
return Alert(
title: Text("Items have to be purchased."),
message: nil,
primaryButton: .default(Text("Purchase"), action: {
purchaseItem()
}),
secondaryButton: .cancel())
case .none, .purchase:
return Alert(title: Text("Purchased!"))
}
}
}